U.S. and U.K. officials are now increasingly focused on the idea that a bomb brought down the Russian jetliner that crashed in Egypt, possibly with the help of an insider who was paid off.
“We have concluded there is a significant possibility that the crash was caused by an explosive device on board the aircraft,” U.K. Foreign Secretary Philip Hammond said Wednesday after Prime Minister David Cameron concluded a meeting of his government’s emergency committee.
Three U.S. officials speaking on condition of anonymity said terrorism was now the leading theory in the case. Preliminary evidence suggested Islamic State involvement and investigators were examining the prospect that someone — perhaps a baggage handler or airline official — was bribed to get a bomb onto the Metrojet airliner, two of the officials said. Other possibilities haven’t been ruled out, the officials said.
The emerging focus on a bomb followed claims by people purporting to represent the Islamic State militants Russia is fighting in Syria who said the jet was downed in retaliation. The U.K. issued an advisory against all but essential travel to or from Egypt’s Sharm el-Sheikh airport, where the doomed plane took off Saturday, and Irish regulators ordered Ireland-based airlines not to fly to the Red Sea resort or the the Sinai Peninsula until further notice.
United Continental Holdings Inc. said it’s rerouting flights away from Sinai, going beyond an existing advisory from the U.S. Federal Aviation Administration for carriers not to fly below 26,000 feet (7,900 meters) in that part of the Middle East due to security concerns. None of the U.S.-based international airlines serves Egyptian markets.
Other governments — including Russia’s — warned that any conclusions are premature and that a structural failure or other cause could explain how the Airbus Group SE A321 broke into pieces and fell to the desert, killing all 224 aboard for the flight to St. Petersburg, Russia. Egyptian Foreign Minister Sameh Shoukry called the U.K. government statement “premature and unwarranted,” according to the BBC.
“Only investigators can have theories,” Kremlin spokesman Dmitry Peskov said by text message. “Everyone has guesses and speculation.”
While the State Department warned employees to avoid the Sinai peninsula, spokesman John Kirby said it was too soon to conclude terrorists destroyed the Metrojet aircraft. “We’re not in a position to make a call right now,” he said. “We don’t know what brought this plane down.”
Confirmation of a bombing would add the jet to a roster of aircraft from multiple countries to have been blown up in flight. The most recent incidents came in 2004, when two Russian passenger aircraft were destroyed in explosions linked to Chechen rebels, according to Richard Bloom, director of terrorism, intelligence and security at Embry-Riddle Aeronautical University in Prescott, Arizona.
“I’ve been worrying about this,” said Hans Weber, an aviation-security specialist and president of consultant Tecop International.
Airport X-ray systems can differentiate between metal and organic material, but inspectors must still hunt for other tell-tale clues such as detonators, wires and batteries, Weber said.
Michael McCaul, chairman of the U.S. House of Representatives Homeland Security Committee, said the Khorasan group, made up of al-Qaeda members operating in Syria, has been developing non-metallic improvised explosive devices that can avoid screening technology.
“One of my concerns about the Russian plane, given the Russian activity now in Syria, is that it possibly could have been one of these non-metallic IEDs,” McCaul said in an interview. “You can’t rule that out at this point in time.”
Recent terrorist efforts to destroy aircraft were notable for their failures. In 2006, U.K. police said they foiled a plot to knock down trans-Atlantic jetliners with liquid explosives, and in 2009 passengers on a Delta jet stopped the so-called underwear bomber, Umar Farouk Abdulmutallab, from destroying a plane en route to Detroit.
Less than a year later, authorities intercepted two packages containing the explosive PETN that were sent from Yemen to synagogues in Chicago via airfreight.
Anthony Skinner, an analyst with U.K.-based forecasting company Verisk Maplecroft, said evidence of Islamic State involvement in the crash would result in stepped-up efforts to fight Islamist groups and further tighten airport security.
“An onboard aircraft bombing would represent a really serious breach of airport security,” Skinner said. “Heads would roll.”
Revised data covering the Metrojet’s final moments show that it slowed suddenly and then plunged to the Earth at 300 miles (483 kilometers) per hour, according to flight-tracking websiteFlightRadar24. The plane fell from 31,000 feet to 26,000 feet in the final 26 seconds, according to the final transmissions from its radio transponder.